The invention relates to a suction device having a suction unit for generating a suction flow and having a suction device housing, in which a dirt collecting chamber is arranged, which has a suction inlet and is flow-connected to the suction unit via at least one filter and an extraction channel arrangement, wherein at least one external air inlet, which can be closed by an external air valve, is arranged on the extraction channel arrangement between the filter and the suction unit, wherein the external air valve has an external air valve body for closing the external air inlet, which external air valve body can be moved, by adjusting an actuating element along an actuation path, between a closed position closing the external air inlet and a passage position releasing the external air inlet, in which external air flowing through the external air inlet flows through the at least one filter in the direction of the dirt collecting chamber for cleaning purposes.
A suction device of this type is described in EP 1 340 446 A1, for example. In this suction device, a so-called counterflow cleaning process is performed. Negative pressure provided by the suction unit is instantaneously applied to the external air valve body to move it into the passage position, so that external air can enter through the external air inlet and flow through the filter in the direction of the dirt collecting chamber, so that particles adhering to the filter are ejected in the direction of the dirt collecting chamber. The closing body is designed as a flap to which a relatively great force provided by an electromagnet has to be applied in the direction of the closed position. The construction is complex and expensive.
WO 2011/003441 A1 discloses a suction device with an external air inlet closed by a valve body which can be actuated from a closed position into an open position by an energy storage device. The energy storage device is supplied with energy for storage by the actuation of an actuating element.
A manual actuation of an external air valve requires force and has to be very fast in order to facilitate an optimum cleaning of the filter by a flow reversal which is as instantaneous as possible. This is difficult in practical applications.